The Collaborative International Dictionary of English v.0.48:

corncob \corn"cob`\ (k[^o]rn"k[o^]b`), n.
   The cob or axis on which the kernels of Indian corn grow.
   [U.S.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

corncob
    n 1: the hard cylindrical core that bears the kernels of an ear
         of corn [syn: corncob, corn cob]